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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="boost_convert.design_notes"></a><a name="quickbook.ref.design_notes"></a><a class="link" href="design_notes.html" title="Design Notes">Design
    Notes</a>
</h2></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="design_notes.html#boost_convert.design_notes.requirements">Requirements</a></span></dt>
<dt><span class="section"><a href="design_notes/converter_signature.html">Converter
      Signature</a></span></dt>
<dt><span class="section"><a href="design_notes/user_interface_signature.html">User
      Interface Signature</a></span></dt>
</dl></div>
<div class="blockquote"><blockquote class="blockquote"><p>
        <span class="bold"><strong><span class="emphasis"><em>"The art of simplicity is a puzzle of
        complexity” Doug Horton</em></span></strong></span>
      </p></blockquote></div>
<p>
      Feel free to skip this section. It is here to document the process and the
      decisions made during design to be able to review and to reevaluate and to
      ensure the relevancy and the correctness of those decisions and ultimately
      the design. Still, this section might be useful for understanding why and how
      certain decisions have been made and why <span class="emphasis"><em>Boost.Convert</em></span>
      is the way it is.
    </p>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_convert.design_notes.requirements"></a><a class="link" href="design_notes.html#boost_convert.design_notes.requirements" title="Requirements">Requirements</a>
</h3></div></div></div>
<p>
        <span class="emphasis"><em>Boost.Convert</em></span> has been designed to satisfy the following
        user requirements:
      </p>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
            <span class="emphasis"><em>(R1)</em></span> <span class="emphasis"><em>Boost.Convert</em></span> shall provide
            a mechanism and an interface that take a value of type <span class="emphasis"><em>TypeIn</em></span>
            and yield a value of type <span class="emphasis"><em>TypeOut</em></span> using an algorithm
            of type <span class="emphasis"><em>Converter</em></span>;
          </li>
<li class="listitem">
            <span class="emphasis"><em>(R2)</em></span> <span class="emphasis"><em>Boost.Convert</em></span> shall provide
            a mechanism and an interface to indicate success or failure of the requested
            conversion;
          </li>
<li class="listitem">
            <span class="emphasis"><em>(R3)</em></span> <span class="emphasis"><em>Boost.Convert</em></span> shall provide
            fully-functional interfaces for two different program flows where
            <div class="orderedlist"><ol class="orderedlist" type="a">
<li class="listitem">
                  <span class="emphasis"><em>(R3a)</em></span> error-processing is orthogonal to the
                  normal program flow (exception-throwing interface);
                </li>
<li class="listitem">
                  <span class="emphasis"><em>(R3b)</em></span> normal and error-processing flows are
                  part of the same program flow (non-throwing interface);
                </li>
</ol></div>
          </li>
<li class="listitem">
            <span class="emphasis"><em>(R4)</em></span> The throwing interface shall return the result
            of successful conversion or shall throw an exception;
          </li>
<li class="listitem">
            <span class="emphasis"><em>(R5)</em></span> The non-throwing interface shall return the
            result and/or some indication of conversion success or failure;
            <div class="orderedlist"><ol class="orderedlist" type="a">
<li class="listitem">
                  <span class="emphasis"><em>(R5a)</em></span> there shall be means to distinguish
                  success from failure;
                </li>
<li class="listitem">
                  <span class="emphasis"><em>(R5b)</em></span> the result of conversion shall only
                  be available when conversion succeeds;
                </li>
<li class="listitem">
                  <span class="emphasis"><em>(R5c)</em></span> when conversion fails, an optional fallback
                  value shall be returned instead if supplied;
                </li>
<li class="listitem">
                  <span class="emphasis"><em>(R5d)</em></span> in the case of failure (with no fallback
                  provided) an attempt to retrieve the result shall result in an
                  exception thrown;
                </li>
</ol></div>
          </li>
<li class="listitem">
            <span class="emphasis"><em>(R6)</em></span> <span class="emphasis"><em>Boost.Convert</em></span> shall provide
            a uniform interface suitable for generic programming;
          </li>
<li class="listitem">
            <span class="emphasis"><em>(R7)</em></span> <span class="emphasis"><em>Boost.Convert</em></span> shall not
            interfere with or intercept any exceptions that are not part of the official
            converter interface (i.e. exceptions caused by malfunction, etc.);
          </li>
<li class="listitem">
            <span class="emphasis"><em>(R8)</em></span> Converters shall be independent of and shall
            not rely on the <span class="emphasis"><em>Boost.Convert</em></span> infrastructure.
          </li>
</ol></div>
</div>
</div>
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<td align="right"><div class="copyright-footer">Copyright © 2009-2020 Vladimir Batov<p>
        Distributed under the Boost Software License, Version 1.0. See copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>.
      </p>
</div></td>
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